PSB file supportYou can now import, catalog, and edit Large Document format (PSB) file in Lightroom Classic. PSB file in Lightroom Classic supports documents up to 65,000 pixels in long edge and a maximum dimension of 512 megapixels. Camera Raw 12.2 is required to use Lightroom Classic's Edit in Photoshop feature with PSB images.
Like all files within Classic, the maximum dimensions are 65,000 pixels on the long edge or 512 megapixels.Layers? No. Not with LR edits.
But maybe a thumbnail will turn up in the catalogue?
Yes indeed, it's only half baked ”support” so it will be interesting to see if the user base accept this well or as I predicted, not so much.